In the exploration for oil and other fossil fuels, a borehole is initially drilled to the depth necessary to reach the reservoir of oil. The drilling equipment is then removed and a casing is placed in the borehole to keep the borehole open. Occasionally, the pressure of the oil will be sufficient to lift the oil to the surface. However, very often it is necessary to pump the oil to the surface.
In the past, pumping units have been positioned on the surface adjacent the borehole. Rigid aligned sucker rods extend from the pumping unit at the surface to a pump within the borehole. The vertical reciprocation of the sucker rods act to operate the pump to lift the oil to the surface. While this technique has been effective, it requires precise positioning of the pumping unit on the surface and the sucker rods are subject to deformation and bending under the loads imposed. Therefore, the need exists for a more cost effective pump for lifting fluids, such as oil.